1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly, to a scroll compressor having a structure capable of causing a portion of oil flowing through an oil passage of a crankshaft to flow out of the crankshaft when the scroll compressor is operated at high speed.
2. Description of the Related Art
As shown in FIG. 1, in a general scroll compressor, a fixed scroll 1 and an orbiting scroll 3 each of which has an involute wrap are engaged with each other to face each other, and therefore a plurality of compression chambers P having large and small crescent shapes are formed by side and bottom surfaces of the fixed scroll 1 and the orbiting scroll 3. Here, the involute wrap of the orbiting scroll 3 is disposed to have a phase difference of 180.degree. with respect to the involute wrap of the fixed scroll 1.
In the above structure, when the orbiting scroll 3 moves in an orbiting motion with respect to the fixed scroll 1, and as a compression chamber having a crescent shape moves toward the center portion of the fixed scroll 1 and the orbiting scroll 3, the volume of the compression chamber is gradually decreased. Consequently, a refrigerant within the fixed scroll 1 and the orbiting scroll 3 is compressed.
Since such a compression operation is continuously and symmetrically performed, the range of variation in load is much narrower than that of a reciprocating compressor or a rotary compressor. Therefore, the scroll compressor is more advantageous than other types of compressors in aspects of vibrations, noises, the efficiency of compression, reliability and the like.
A conventional scroll compressor will be described in detail with reference to FIG. 2. In a conventional scroll compressor, a refrigerant which flows in the compressor through a suction pipe 5 is supplied to the inside of a fixed scroll 1 and an orbiting scroll 3 through a suction port formed at one side of the fixed scroll 1.
At the same time, when electric power is supplied to the stator 7 of a motor, the rotor 9 positioned inside of the stator 7 rotates. In addition, a crankshaft 11 is fixedly inserted in the center portion of the rotor 9, and as the crankshaft 11 rotates with the rotor 9, the orbiting scroll 3 fixed to an eccentric end of the crankshaft 11 moves in an orbiting motion.
At this time, the orbiting scroll 3 revolves without rotating about the fixed scroll 1 by an Oldham ring 15 seated between a main frame 13 and the orbiting scroll 3, and the crankshaft 11 is supported by the main frame 13 and a sub-frame 17 at the upper and lower ends of the crankshaft 11, respectively.
Then, as a compression chamber P is moved toward the center portion by mutual motion of the fixed scroll 1 and the orbiting scroll 3, the volume of the chamber P is gradually decreased, and the refrigerant within the compression chamber P is compressed. The refrigerant thus compressed by the fixed scroll 1 and the orbiting scroll 3 is supplied to a discharge pipe 19 through a discharge port formed at the center portion of the fixed scroll 1, and is then discharged to the outside of the compressor through the discharge pipe 19 and circulated into a refrigeration cycle mechanism.
In addition to the above structure for compressing the refrigerant, the scroll compressor includes a structure for smoothly lubricating a compression portion and a mechanical portion. Such a lubricating structure includes an oil storing portion 21 installed for storing oil at the lower portion of the compressor, an oil passage 12 formed through the inside of the crankshaft 11 so that the oil within the oil storing portion 21 can be delivered to the compression portion and the mechanical portion, and an oil pump 23 for supplying the oil within the oil storing portion 21 to the oil passage 12. Usually, a centrifugal pump, a volummetric pump, a pressure difference pump or the like is used as an oil pump.
However, since, in the above conventional scroll compressor, the amount of oil supplied by the oil pump 23 is increased in proportion to the rpm of the compressor, oil is excessively supplied when the compressor is operated at high speed and the amount of oil supplied to the compression portion is increased. Accordingly, the amount of discharged oil is increased, and there is a problem in which the efficiency of volume of the compressor is lowered.